Russia’s war on Ukraine shows no sign of ending, but it is not too soon to start thinking about how to ensure postwar Ukraine’s stability, prosperity and security.

Already, two discussions are occurring: one about financing economic reconstruction and the other about affirming Ukraine’s external security. The problem is that these discussions are proceeding separately, even though the issues are intimately related.

Reconstruction costs are uncertain because the course of the war is uncertain. Ukraine’s prewar gross domestic product was some $150 billion. Given a capital-output ratio of three, and assuming that a third of the capital stock will be destroyed, we are again talking about $150 billion. As always, alternative assumptions yield alternative scenarios, but $150 billion seems like a reasonable starting point.